The present invention is useful in excavating hard rocky formations such as encountered in the building of highways and in the operation of a quarry or a mine, and wherever the removal of a large overburden of material is necessary in order to gain possession of the underlying minerals or paydirt.
This invention is especially useful for the removal of a layer of earth or rock that is hundreds of acres in area and more than 100 foot thick, for example. The economics of such a monumental task requires specially designed digging equipment of a tremendous size that usually is assembled at the mine where it remains during its entire life. This is because a ground supported vehicle that can more efficiently dig through and excavate great quantities of rock is too large and too heavy to be transported down a roadway or a railway. Therefore, should it become necessary or desirable to move such a large digging machine, it must first be dismantled into several sections in order to reduce the machine into smaller packages, each being of a manageable size and weight, to thereby facilitate changing job sites.
By the present invention it has been found advantageous to provide such a digging machine with a mid-section located at the longitudinal center of gravity and between opposed ends thereof, with there being a digging apparatus having a mining drum that is wider than the vehicle and is attached at the lower part of the vehicle mid-section to assure that the entire machine can traverse a deep cut as it is being formed, and also to dig immediately adjacent any structure. Additionally, provision is made by which the digging apparatus of such a vehicle can be extended against the ground with a force that is equal to the entire weight of the vehicle, and thereby apply an unusually large load onto the digging teeth of the digging apparatus as it digs into and excavates the ground. Gigantic supercharged diesel engines are available that can supply the enormous amount of power required for rotating such a huge digging apparatus under these unusual excavating conditions.
Heretofore, some extremely large excavating machines, that is, those weighing near 200 tons, have employed endless digging apparatus having digging teeth of various design mounted thereon, with the digging apparatus being indirectly mounted to the vehicle main frame in a manner to enable movement thereof respective to the main frame of the vehicle in order to adjust the drive chain tension thereof, and to adjust the depth of penetration of the digging apparatus respective to the ground. It has been discovered that when the digging teeth of these large prior art excavating machines are forced against the hard or rocky ground with sufficient power input and speed to achieve a good rate of penetration, undesirable vibration and chattering of the digging apparatus, including the digging teeth and the drive train, results from the interaction of the digging teeth with the hard formation as the teeth engage and excavate the formation or earth. This described action induces harmonic motion into the structure which oscillates at frequencies which breaks the teeth and unduly accelerates wear of the drive train, thereby requiring excessive maintance. Accordingly, heretofore it has not been possible to increase the load on the teeth of the digging apparatus while concurrently increasing the power input thereto in the manner taught herein.
By the present invention, there is provided a quarry miner or digging machine having a digging apparatus that includes a mining drum rotatably received on a shaft. The shaft is directly mounted to the vehicle main frame in order to reduce vibratory motion to a minimum. The mining drum is driven by an endless ladder type excavating apparatus that also forms part of the mining drum as well as the drive chain therefor. This arrangement allows the rotating ground engaging parts thereof to be rigidly mounted respective to the main frame of the vehicle. It has been discovered that this novel arrangement of the digging apparatus of a large excavating machine minimizes the vibrational problems cited above and consequently the digging teeth thereof can be forced against the hard or rocky ground with sufficient force to acheive an unexpected improvement in the rate of penetration. Reducing the maintance by reducing these undesirable vibrational forces along with reducing the induced chattering of the components of the digging apparatus allows an unexpected increased application of weight and power to the digging apparatus to be gained, whereby increased penetration rate, increased depth of the cut, and reduced wear on the digging apparatus and the drive train is realized.
Accordingly, by the present invention it is possible to increase the load on the digging teeth of the digging apparatus while concurrently increasing the power input thereto in a manner not heretofore possible.
Further, the present invention teaches improvements in translocating the excavated material from the ground onto a special conveyor system by the employment of a mold board in combination with the improved digging apparatus and a novel conveyor system therefor. The improved conveyor system translocates the excavated material from the centrally located digging apparatus to an unusually long conveyor system that can be raised or lowered, as well as swung in an arc, so as to reach out and discharge material far away from the digging apparatus. This enables the excavated material to be redeposited in the mined out area, and most important of all, to load the paydirt into appropriate conveyance means by which the paydirt can be translocated to a suitable processing facility.
Apparatus that overcomes the foregoing problems and achieves these and other desirable goals is the subject of this invention.